RUI: Contribution of Retinal Melatonin to Circulating Melatonin and its Importance in Metamorphosis

这项研究将研究眼部褪黑激素的分泌，以及这种褪黑激素在两栖动物变态过程中的作用。脊椎动物眼睛的功能并不局限于视觉。有关环境光照周期的信息通过眼睛传递到昼夜节律系统，在许多非哺乳动物脊椎动物中，眼睛中的视网膜为循环贡献褪黑素。关于两栖动物眼部褪黑激素分泌的程度，人们知之甚少。眼球切除技术将被用来确定无尾两栖类蝌蚪不同发育阶段眼睛对血液褪黑素的相对贡献，以及视网膜褪黑素、甲状腺激素和变态之间的关系。该项目还将研究明/暗周期对循环视网膜褪黑素的影响，视网膜褪黑素分泌与循环褪黑素和甲状腺素的昼夜节律之间的关系，以及为了维持血液褪黑素水平，单侧或双侧眼球摘除后是否会出现褪黑素的代偿性增加。这些研究将提高我们对褪黑素在发育中的作用以及它与光周期对变态的影响的关系的理解。这项研究的发现可能对研究激素相互作用和褪黑激素在脊椎动物中的作用也有意义。此外，这些结果可能有助于更好地理解影响两栖动物数量下降的环境因素。这个项目将在本科生中进行，以培养他们的研究能力和经验，并提升他们的职业抱负。打算在大学任教的博士后研究员也将合作一年，以获得大学层面的教学和研究相结合的经验。因此，该项目将极大地促进国家科学基金会的目标，即鼓励将研究整合到本科项目中，并在促进教学、培训和学习的同时促进发现。

This study will examine the ocular secretion of melatonin and the role of this melatonin in amphibian metamorphosis. The function of the vertebrate eye is not restricted to vision. Information about the environmental lighting cycle is conveyed to the circadian system via the eye and, in many nonmammalian vertebrates, the retina in the eye contributes melatonin to the circulation. Little is known about the extent of ocular melatonin secretion in amphibians. The technique of opthalmectomy will be used to determine the relative contribution of the eye to blood melatonin at different developmental stages in anuran tadpoles, as well as the relationships between retinal melatonin, thyroid hormones, and metamorphosis. This project will also examine light/dark cycle influences on circulating retinal melatonin, the association between retinal melatonin secretion and the diel rhythms in circulating melatonin and thyroxine, and whether a compensatory increase in melatonin production occurs after unilateral or bilateral opthalmectomy in an effort to maintain blood melatonin levels. These studies should improve our understanding of the role of melatonin in development and its relationship to photoperiodic influences on metamorphosis. The findings of this research might have significance as well to the study of hormone interactions and the role of melatonin in vertebrates in general. Moreover, these results may contribute to a better understanding of the environmental factors that affect declining amphibian populations. This project will be carried out with undergraduate students, to develop their competence and experience in research and to upgrade their career aspirations. A postdoctoral fellow who intends to seek a career in college teaching will also collaborate for one year to acquire experience in combining teaching and research at the college level. Thus, the project will contribute substantially to the National Science Foundation's objective of encouraging the integration of research into undergraduate programs and to advance discovery while promoting teaching, training, and learning.